Condensation on Glass

Will your gorgeous, yet slightly old sash windows last the winter? If you’re lucky enough to have original Victorian windows in your house, the hard December winds and bitter January snow can quickly remind you that, whilst beautiful, there is something to be said about well-insulated, draught- and condensation-free windows.

Whilst professional (or DIY) draught-proofing can dramatically increase the amount of heat kept in, glass often remains cold which can be a focal point for condensation. Read on for our top tips about what can be done to ensure you’re still able to gaze out on the world from the comfort of your sofa…

What causes condensation?

Our British air is often saturated with moisture. When this cold, moist air hits cold surfaces it turns back into water droplets which we see as condensation.

Why is it bad news?

Condensation can indicate that the humidity inside your home is excessive. If it isn’t dealt with swiftly it can result in unsightly black mould growing around windows and on the walls and ceilings in your home. With mould come health complications – such as sinus problems, rashes, and potentially bronchitis. The damp can also cause wood rot, plaster damage, and more.

Can you identify the source of the problem?

The location of the condensation on your windows can help identify the source. If it is:

  • On the outside, this is normal and there is nothing to worry about
  • On the inside of the glass, then read on

If you have condensation between two panes of glass, you may well have an airtight, sealed, double-glazed unit and it could be that the seal has failed.

Can I reduce interior condensation?

Yes, it is possible to reduce condensation. The basic principle is to either increase the heat or reduce the humidity levels in your home.
You can do this by:

  • Raising the temperature, as condensation occurs when warm air hits cold surfaces (in this case your windows)
  • Turning down any humidifiers in use
  • Buying a dehumidifier to reduce moisture levels
  • Making sure you use bathroom and kitchen fans
  • Opening windows after showers or baths and during cooking to ventilate and circulate air around the room
  • Moving plants from problem areas – if your living room resembles a jungle, shift some of them to another room. Plants release moisture, increasing the humidity level in your room

What if the condensation persists?

You may need to look at replacing the glass units. If you’re in a position to replace the glazing you will:

  • Notice a significant reduction in heat loss
  • Retain the look of the period windows as you’ll be utilising the original frames and boxes

If you are considering installing sash or casement windows, or are looking to repair existing ones, our team at Wandsworth Sash Windows would love to talk to you. Call us on 020 3733 3575 with any questions you may have or to make an appointment.

Contact the Wandsworth Sash Windows team

Talk to us – we can help with your bespoke window, door and joinery requirements. Call 02079247303 or email